Push to start mechanism



Aug. 2, 1966 w. M. JENKINS PUSH TO START MECHANISM 2 Sheets-Sheet 1 Filed Oct. 22, 1964 INVENTOR. W/L L/AM M. JE/VK/IVS ATTORNEY Aug. 2, 1 w. M. JENKINS PUSH TO START MECHANISM 2 Sheets-Sheet 2 Filed 001;. 22, 1964 FIG. 5'

INVENTOR. M. c/E/VK/NS WILL/AM ATTORNEY United States Patent 3,264,441 PUSH TO START MECHANISM William M. Jenkins, Indianapolis, Ind, assignor to I. R. Mallory & Co. Inc., Indianapolis, Ind, a corporation of Delaware Filed Oct. 22, I964, Ser. No. 405,687 11 Claims. (Cl. 200-153) The present invention relates to switch mechanisms, more particularly to a pushto-start switch mechanism that may be utilized to actuate a sequential timer and the like. The push-pull switch mechanism is employed to provide a means for the instantaneous initiation of a timing cycle and to provide a means for automatic termination of the timing cycle. The termination of the timing cycle is accomplished in such a manner that the switch mechanism is positioned at its starting location.

In a device of this general nature it is desirable that the push-to-start switch mechanism necessarily incorporate therein a rotatable cam-carrying shaft which cooperates with a plurality of electrical circuits so as to sequentially actuate said circuits, a compression spring means, a cantilever spring means, an index means, a mounting frame, and a line switch means.

Several push-to-start switch means presently available are utilized to initiate the operation of a timing cycle. However, these several push-to-start switch means utilize a shaft means that is displaced manually through a predetermined arc to an initial position indicated by indicia on the shaft, thereafter, the shaft is displaced inwardly to initiate a timing cycle. In the several presently available push to start mechanisms, the mechanisms deenergize the control timer prior to the shaft of the mechanism rotating through 360 degrees, thereby creating dead space on the shaft; that is, a space on the shaft that is not utilized. The reason for the deactuation of the timer prior to a 360 degree rotational displacement of the shaft is that the timer must be deactuated prior to the shaft reaching its actuation point or the timer will perpetually cycle.

In contrast to the several presently available mechanisms, the present invention provides a push-to-start switch mechanism wherein the mechanism is automatically positioned at the actuation point of the mechanism when the mechanism terminates the timing cycle. It is seen that the shaft of the mechanism is positioned to initiate another timing cycle without the necessity of manually resetting any of the components of the push to start mechanism. The invention comprises a simple, efficient, inexpensive, accurate, and effective push to start mech anism that includes a shaft rotated unidirectionally at a slow, intermittent speed by a prime mover. The prime mover is actuated by the manual inward displacement of the shaft of the push to start mechanism. The slow, intermittent moving shaft provides a driving force that actuates a cam means that in turn controls the sequential operation of a plurality of switch means of a control timer.

It is an object of the present invention to provide a novel push to start mechanism that is prepared for actuation at the termination of a timing cycle without rotationally resetting any components thereof,

Still another object of the present invention is to provide a push to start mechanism that is simple to fabricate and easy to assemble.

A further object of the present invention is to provide a push to start mechanism that cannot be inadvertently deactuated after the mechanism has been actuated.

Still another object of the present invention is to provide a push to start mechanism for actuating a control timer, said mechanism being inexpensive and accurate in construction.

A further object of the present invention is to provide a push to start mechanism having a shaft that is unidirectionally rotated at a slow, intermittent speed.

The present invention in another of its aspects relates to novel features of the instrumentalities of the invention described therein for teaching the principal object of the invention and to the novel principles employed in the instrumentalities whether or not these features and principles may be used in the said object and/or in the said field.

With the aforementioned objects enumerated, other objects will be apparent to those persons possessing ordinary skill in the art. Other objects will appear in the following description, the appended claims, and the appended drawing. The invention resides in the novel construction, combination, arrangement, and the cooperation of elements as hereinafter described and more particularly as defined in the appended claims.

The appended drawing illustrates the preferred embodiment of the present invention constructed to function in the most advantageous modes devised for the practical application of the basic principles involved in the hereinafter described invention.

In the drawings:

FIGURE 1 is a perspective view of the present invention illustrating the push to start mechanism and associated prime mover.

FIGURE 2 is an exploded view of the present invention.

FIGURE 3 is a partial perspective view of the present invention illustrating the initial position of an index means of the push to start mechanism.

FIGURE 4 is a partial perspective view of the present invention illustrating the initial on position of the index means of the push to start mechanism.

FIGURE 5 is a partial bottom view of the present invention illustrating the initial on position of the index means of the push to start mechanism.

FIGURE 6 is a partial bottom view of the present invention illustrating the on position and the off position of the index means in full and dotted lines respectively.

Generally speaking, the present invention relates to the means and methods of actuating a sequential timer, more particularly to a push to start mechanism that has a terminating point on a rotatable shaft positioned at the initiation point of the rotatable shaft. The push to start mechanism utilizes the cooperation between an apertured mounting frame, a rotatable indexing means, a shaft, and a cantilever spring means to accomplish the aforementioned novel result. A cam-carrying shaft is rotatably journalled within the aperture of the mounting frame. A plurality of cams are fixedly coupled to the shaft. A compression spring means is utilized to bias the shaft outwardly from the mounting frame. An index means is fixedly coupled to the shaft and is rotatable therewith. The index means includes a projection that slidably interfits with the aperture in the mounting frame. The cantilever spring means is fixedly coupled to the mounting frame and is biased against the projection of the index means. A contact switch means includes a first contact carrying blade and a second contact carrying blade. The first contact blade is biased by one of the plurality of cams away from the second contact carrying blade when the projection of the index means interfits with the aperture. The shaft is manually displaced inwardly to initiate the timing cycle and in so doing thereby stores energy during the displacement of the compression spring. Thereafter, an arm of the cantilever spring means is displaced so as to be positioned across the aperture of the mounting frame. The position of the arm of the torsion spring means prevents the return of the projection of the index means to an interfitting position with the aperture. The inward displacement of the shaft also displaces inwardly the cam engaging the contact switch means. The displacement of the cam allows the first contact blade to engage the second contact blade thereby completing an electrical circuit through the contact switch. Means are coupled to the shaft to rotatably displace the cam-carrying shaft and the index means carried on the shaft. Rotation of the index means engages the arm of the cantilever spring means after a predetermined accurate displacement thereof. Further rotation of the index means displaces the cantilever spring means outwardly, thereby allowing the projection of the index means to interfit with the aperture of the mounting frame. The shaft is displaced outwardly by the energy stored in the compression spring, thereby allowing one of the cams to engage the first contact carrying blade. The cam displaces the first blade breaking the engagement of the first blade with the second blade, thereby opening the electrical circuit. The push to start mechanism is positioned on the start position without the need of rotatably resetting any of the components of the mechanism.

Referring now to FIGURE 1 of the drawing which illustrates the preferred embodiment of the present invention comprising control timer 22 of which push to start mechanism 23 is an integral component thereof.

The exploded view of FIGURE 2 more clearly illustrates the novel features of the push to start mechanism 23. An apertured mounting frame 13 is utilized to rotationally journal cam-carrying shaft thereto by means of a keyhole-shaped aperture 24. The cam-carrying shaft has opposite sections of its periphery milled substantially flat as shown in FIGURE 2. An index means 12 includes a centrally located. aperture that interfits with shaft 10, thereby fixedly coupling the index means by press fitting or any other suitable means on the shaft. It is seen that the index means is mounted in a predetermined position with respect to a point such as the initiation point and the termination point on the periphery of the shaft. A plurality of cams 15 are mounted on the shaft in a manner similar to that of the index means. The keyholeshaped aperture in the mounting frame is so dimensioned that a projection 25 of the index means slidably interfits with a stop portion of the keyhole-shaped aperture. The interfitting occurs when the index means is in the initial position as shown in FIGURE 3.

A compression spring means 14 is carried on the camcarrying shaft between the mounting frame and washer 18. Washer 18 is carried on the shaft. Washer 18 is retained in position by ring 19 which is press fitted with the shaft by any suitable means. It is seen that spring means biases the cam-carrying shaft outwardly from the mounting frame, thereby displacing projection 25 of the index means into engagement with the keyhole-shaped aperture of the mounting frame. The retaining ring is predeterminately spaced from the mounting frame so that the desired amount of spring tension is maintained on the shaft.

A cantilever spring means 11 is fixedly coupled to the mounting frame by any suitable means such as rivet 21. Extremity 26 of the cantilever spring means projects through an aperture in the mounting frame. Extremity 26 and rivet 21 cooperate to bias arm 27 of the cantilever spring means toward the projection of the index means. The arm of the cantilever spring means is so formed that when the cantilever spring means is located in position, the spring means is biased toward the index means so as to maintain engagement therewith throughout the entire rotational displacement of the index means. A sleeve carried on the cam carrying shaft serves to predeterminately space a cam 15 carried on the shaft from the index means. Fixedly coupled to wall 28 of the push to start mechanism is contact switch 31. The contact switch is comprised of a contact carrying blade means 16 and contact carrying blade bracket means 17. 'Both of the contact carrying blade means are fabricated from any suitable resilient and electrically conducting metal. Contact carrying means 16 includes protrusion 29 that rides on the surface of cam 15 under predetermined conditions. The protrusion 29 maintains the contact of contact carrying blade means 16 a predetermined distance from cam 15. When the contact of blade means 16 engages the contact of bracket blade means 17, the control timer coupled thereto is electrically energized. When the contact of the blade means 16 disengages the contact of blade bracket means 17, the control timer coupled thereto is electrically deenergized.

In operation the initial or off position of the push to start mechanism is shown in FIGURES 3 and 5. The projection 25 is shown as interfitting with the keyhole aperture of the mounting frame. The arm of the cantilever spring means is biased against the periphery of the index means. Cam 15 and protrusion 29 of blade means 16 bias, the contact of contact carrying blade means 16 away from the contact of blade means 17 to thereby deenergize the control timer associated with the contact switch means. The cam is retained in this position by the energy of the compression spring 14 acting to displace washer 18 away from mounting frame 13.

FIGURE 4 illustrates the index means immediately after shaft 10 is displaced inwardly by any suitable manual or mechanical means. As the shaft is displaced inwardtly, the compression spring means 15 is further compressed thereby storing additional energy. As the shaft is displaced inwardly, cam 15 fixedly carried on the shaft no longer biases the contact of the cont-act carrying blade 16 away from the contact carried by the contact carrying blade bracket means 17, thereby allowing the contact carried by means 16 to engage the contact carried by means 17. Upon engagement a power source (not shown) is coupled to the control timer, thereby energizing the control timer. It is seen that arm 27 of the cantilever spring means falls between projection 25 and keyhole-shaped aperture 24, thereby effectively preventing a return of the projection to an interfitting position with the keyhole-shaped aperture, thus insuring that the contact carrying blade means 16 and 17 remain engaged.

A prime mover 30 is coup-led to the cam-carrying shaft by a plurality of speed reduction gears (not shown). It is seen that the prime mover, through the operation of the speed reduction gears, is used to drive the shaft through a 360 degree revolution at a predetermined speed. As the shaft rotates, the index means fixedly coupled thereto rotates therewith so that the projection arcuately slides along the periphery of the cantilever spring means and the projection arcuately slides along the surface of the mounting frame.

FIGURE 6 shows the index mechanism nearly completing a timing cycle. At this point, the projection of the index means which is arcuately sliding at a predetermined rate of speed along the mounting frame contacts the arm of the cantilever spring means. Continued rotational dis-' placement of the index means and associated projection progressively actuates the arm of the cantilever spring away from the cam-carrying shaft. As illustrated by the dotted lines of FIGURE 6, the projection displaces the arm :of the torsion spring means so that the arm no longer prevents the interfitting 0f the projection of the index means with the keyhole-shaped aperture of the mounting frame. As shown by the dotted lines of FIGURE 6 when projection 25 overlies the keyhole-shaped aperture, the energy stored in the compression spring displaces the projection such that the projection interfits with the keyholeshaped aperture. In a like manner the shaft and the cams carried thereby are displaced such that cam 15 engages protrusion 29 of the contact carrying blade means 16, thereby displacing the blade and associated contact away from blade means 17 and its associated contact. When the disengagement of the contacts occurs, the timer is deenergized, thereby terminating the timing cycle with the push to start mechanism position at its initial starting position. As disclosed hereinbefore the push to start mechanism and hence the control timer can be restarted merely by depressing the cam carrying shaft without the need of resetting the control timer.

While the invention is illustrated and described in its preferred embodiment, it will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of this invention as set forth in the appended claims.

Having thus described my invention, I claim:

1. A push to start switch mechanism comprising: an apertured mounting frame; a shaft rotatably journalled Within said apertured mounting frame; a compression spring means biasing said shaft outwardly from said mounting frame; an index means coupled to said shaft, said index means including means interfitting with said aperture of said mounting frame; a spring means fixedly coupled to said mounting frame and biased against said means of said index means; a contact switch means carried by said mounting frame, said switch inctuding disengaged contacts when said means interfits with said aperture; means to push said shaft inwardly storing energy in said compression spring means, said spring means biased across said aperture as said means is displaced therefrom, preventing said means from interfitting with said aperture, said contacts engaged as a result of said inward movement of said shaft, thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said spring means upon an arcuate displacement of said index means, said index means displacing said spring means allowing said means to interfit with said aperture, said shaft displaced outwardly by the releasing of the energy stored in said compression spring means, said outward displacement of said shaft disengaging said contacts.

2. A push to start switch mechanism comprising: an apertured mounting frame; a shaft rotatably journalled within said apertured mounting frame; a compression spring means biasing said shaft outwardly from said mounting frame; an index means coupled to said shaft, said index means including a projection slidably interfitting with said aperture of said mounting frame; a spring means fixedly coupled to said mounting frame and biased against said projection of said index means; a contact switch means carried by said mounting frame, said switch including disengaged contacts when said projection interfits with said aperture; means to push said shaft inwardly, storing energy in said compression spring means, said spring means biased across said aperture as said projection is displaced therefrom, preventing said means from interfitting with said aperture, said contacts engaged as a result of said inward movement of said shaft, thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said spring means upon an arcuate displacement of said index means, said index means displacing said spring means allowing said projection to interfit with said aperture, said shaft displaced outwardly by the releasing of the energy stored in said compression spring means, said outward displacement of said shaft disengaging said contacts.

3. A push to start switch mechanism comprising: an apertured mounting frame; a shaft rotatably journalled within said apertured mounting frame; a compression spring means biasing said shaft outwardly from said mounting frame; an index means coupled to said shaft, said index means including a projection slidably interfitting with said mounting frame; a cantilever spring means including an arm means fixedly coupled to said mounting frame, said arm means biased against said projection of said index means; a contact switch means carried by said mounting frame, said switch including disengaged contacts when said projection interfits with said aperture; means to push said shaft inwardly, storing energy in said compression spring means, said arm means biased across said aperture as said projection is displaced therefrom, preventing said means from interfitting with said aperture, said contacts engaged as a result of said inward movement of said shaft, thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said arm means upon an arcute displacement of said index means, said index means displacing said arm means allowing said projection to interfit with said aperture, said shaft displaced outwardly by the releasing of the energy stored in said compression spring means, said outward displacement of said shaft disengaging said contacts.

4. A push to start switch mechanism comprising: an apertured mounting frame including a keyhole-shaped aperture, a shaft rotatably journalled within said keyholeshaped aperture; a compression spring means biasing said shaft outwardly from said mounting frame; an index means fixedly coupled to said shaft, said index means including a projection slidably interfitting with said keyhole-shaped aperture of said mounting frame; a spring means including an arm means fixedly coupled to said mounting frame, said arm means biased against said projection of said index means; a contact switch means carried by said mounting frame, said switch including disengaged contacts when said projection interfits with said keyhole-shaped aperture; means to push said shaft inwardly, storing energy in said compression spring, said arm means biased across said keyhole-shaped aperture as said projection is displaced therefrom,-said contacts engaged by said shaft as a result of said inward movement of said shaft, thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said arm means after a predetermined arcuate displacement of said index means, said index means displacing said arm means allowing said projection to interfit with said keyhole-shaped aperture, said shaft displaced outwardly by the energy stored in said compression spring, said outward displacement of said shaft disengaging said contacts.

5. A push to start switch mechanism comprising: an apertured mounting frame including a keyhole-shaped aperture, rotatably journalled within said keyhole-shaped aperture; an index means fixedly coupled to said shaft, said index means including a projection interfitting with said keyhole-shaped aperture of said mounting frame; a spring means including an arm means fixedly coupled to said mounting frame, said arm means biased to the proximity of said index means, a contact switch means carried by said mounting frame, said switch including disengaged contacts when said projection interfits with said keyholeshaped aperture; means to push said shaft inwardly, said arm means biased across said keyhole-shaped aperture as said projection is displaced therefrom, said contacts engaged by said shaft as a result of said inward movement of said shaft; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said arm means after a predetermined arcuate displacement of said index means, said index means displacing said arm means allowing said projection to interfit with said keyhole-shaped aperture, said shaft displaced outwardly, said outward displacement of said shaft disengaging said contacts.

6. A push to start switch mechanism comprising: an apertured mounting frame; a cam carrying shaft rotatably journalled by said aperture mounting frame; a plurality of cams fixedly coupled to said shaft; a compression spring means biasing said shaft outwardly from said mounting frame; an index means fixedly coupled to said shaft, said index means including a projection slidably interfitting with said aperture of said mounting frame; a cantilever spring means including an arm means fixedly coupled to said mounting frame, said arm means biased against said projection of said index means; a contact switch means ineluding a first contact carrying blade and a second contact carrying blade, said first contact carrying blade biased by one of said cams away from said second contact carrying blade when said projection interfits with said aperture; means to displace said shaft inwardly storing energy in said compression spring, said arm means biased across said aperture as said projection is displaced therefrom, said cam displaced by said shaft as a result of said inward movement of said shaft allowing said first contact blade to engage said second contact blade thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said arm means after a predetermined arcuate displacement of said index means, said index means displacing said arm means allowing said projection to interfit with said aperture, said shaft displaced outwardly by the energy stored in said compression spring thereby allowing said cam to engage said first contact carrying blade, said cam displacing said first blade breaking engagement of said first blade with said second blade.

7. A push to start switch mechanism comprising: an apertured mounting frame including a keyhole-shaped aperture; a cam carrying shaft rotatably journalled within said keyhole-shaped aperture; a plurality of cams fixedly coupled to said shaft; a compression spring means biasing said shaft outwardly from said mounting frame; an index means fixedly coupled to said shaft, said index means including a projection slidably interfitting with said keyhole-shaped aperture of said mounting frame; a cantilever spring means including an arm means fixedly coupled to said mounting frame, said arm means biased against said projection of said index means; a cont-act switch means carried by said mounting frame, said switch including a first contact carrying, blade and a second contact carrying blade, said first contact carrying blade biased by one of said cams away from said second contact carrying blade when said projection interfits with said keyholeshaped aperture; means to push said shaft inwardly, storing energy in said compression spring, said arm means biased across said keyhole-shaped aperture as said projection is displaced therefrom, said cam displaced by said shaft as a result of said inward movement of said shaft allowing said first contact blade to engage said second contact blade, thereby completing an electrical circuit through said contact switch; and means coupled to said shaft to rotatably displace said shaft and said index means, said index means engaging said arm means after a predetermined arcuate displacement of said index means, said index means displacing said arm means allowing said projection to interfit with said keyhole-shaped aperture, said shaft displaced outwardly by the energy stored in said compression spring thereby allowing said cam to engage said first contact carrying blade, said cam displacing said first blade breaking engagement of said first blade with said second blade.

8. A push to start mechanism comprising: a mounting frame; an axially displaceable shaft rotatably journalled to said mounting frame; an index means carried by said shaft, said index means normally restrained by a stop means on said mounting frame thereby preventing rotational displacement of said shaft; a bias means fixedly coupled to said mounting frame and positioned against said index means, axial displacement of said shaft repositioning said bias means so as to prevent said stop means from prohibiting rotational displacement of said shaft; and means coupled to said shaft to rotatably displace said shaft and said index means, after predetermined arcuate displacement said index means engages said bias means and displaces said bias means causing said index means to engage with said stop means thereby terminating arcuate displacement of said shaft.

9. A push to start mechanism comprising: a mounting frame; an axially displaceable shaft rotatably journalled to said mounting frame; an index means carried by said shaft, said index means normally restrained by a stop means on said mounting frame thereby preventing rotational displacement of said shaft; a bias means fixedly coupled to said mounting frame and having a free end positioned against said index means, inward axial displacement of said shaft repositioning said free end of said bias means so as to prevent said stop means from prohibiting rotational displacement of said shaft; and means coupled to said shaft to rotatably displace said shaft and said index means, after predetermined arcuate displace ment said index means engages said free end of said bias means and displaces said free end of said bias means causing said index means to engage with said stop means thereby terminating arcuate displacement of said shaft and displacing said shaft outwardly.

10. A push to start mechanism comprising: an apertured mounting frame; an axially displaceable shaft rotatably journalled to said mounting frame; an index means carried by said shaft, said index means including a projection normally interfitting with said aperture of said mounting frame thereby preventing rotational displacement of said shaft; a cantilever spring means fixedly coupled to said mounting frame and having a free end biased against said projection of said index means, inward axial displacement of said shaft repositioning said free end of said cantilever spring means so as to be biased over said aperture thereby prohibiting said projecting from interfitting with said aperture so as to allow rotational displacement of said shaft; and a prime mover means coupled to said shaft to rotatably displace said shaft and said index means, after predetermined arcuate displacement said projection of said index means engages said free end of said cantilever spring means and displaces said free end of said cantilever spring means allowing said projection of said index means to interfit with said aperture of said mounting frame thereby terminating arcuate displacement of said shaft and displacing said shaft outwardly.

11. A push to start switch mechanism comprising: an apertured mounting frame; an axially displaceable cam carrying shaft rotatably journalled to said mounting frame; a normally open contact switch means carried by said mounting frame; an index means carried by said shaft, said index means including a projection normally interfitting with said aperture of said mounting frame thereby preventing rotational displacement of said shaft; a cantilever spring means fixedly coupled to said mounting frame and having a free end biased against said projection of said index means, inward axial displacement of said shaft repositioning said free end of said cantilever spring means so as to be biased over said aperture thereby prohibiting said projection from interfitting with said aperture so as to allow rotational displacement of said shaft, inward axial displacement of said shaft causes said came to disengage with said switch closing said switch contacts; and prime mover means coupled to said shaft to rotatably displace said shaft and said index means when said contacts of said switch are closed, after predetermined arcuate displacement said index means engages said free end of said cantilever spring means and displaces said free end of said cantilever spring means allowing said projection of said index means to interfit with said aperture of said mounting frame thereby terminating arcuate displacement of said shaft and displacing said shaft outwardly causing said cam to engage said switch opening said switch contacts.

References Cited by the Examiner UNITED STATES PATENTS 3,166,714 1/1965 Vo Dinh Hien 200-156 X BERNARD A. GILHEANY, Primary Examiner.

G. MAIER, Assistant Examiner. 

1. A PUSH TO START SWITCH MECHANISM COMPRISING: AN APERTURED MOUNTING FRAME; A SHAFT ROTATABLY JOURNALLED WITHIN SAID APERTUREED MOUNTING FRAME; A COMPRESSION SPRING MEANS BIASING SAID SHAFT OUTWARDLY FROM SAID MOUNTING FRAME; AN INDEX MEANS COUPLED TO SAID SHAFT, SAID INDEX MEANS INCLUDING MEANS INTERFITTING WITH SAID APERTURE OF SAID MOUNTING FRAME; A SPRING MEANS FIXEDLY COUPLED TO SAID MOUNTING FRAME AND BIASED AGAINST SAID MEANS OF SAID INDEX MEANS; A CONTACT SWITCH MEANS CARRIED BY SAID MOUNTING FRAME, SAID SWITCH INCLUDING DISENGAGED CONTACTS WHEN SAID MEANS INTERFITS WITH SAID APERTURE; MEANS TO PUSH SAID SHAFT INWARDLY STORING ENERGY IN SAID COMPRESSION SPRING MEANS, SAID SPRING MEANS BIASED ACROSS SAID APERTURE AS SAID MEANS IS DISPLACED THEREFROM, PREVENTING SAID MEANS FROM INTERFITTING WITH 